1. Field of the Invention
The present invention relates to a disc brake and more specifically to an improved dual rotor disc brake utilizing spot or segment type friction pads.
Spot or segment friction pads are utilized in disc brakes to provide friction means adjacent oppositely disposed surfaces of a rotor at a predetermined spot or segment of the rotor thereby permitting a substantial portion of the rotor which is not located between the friction pads to rotate through and be exposed to ambient air in the vicinity of the vehicle wheel to dissipate thermal energy resulting from the pressurized contact of the friction pads with the rotor. Such an arrangement provides an efficient air cooled brake for use on automotive vehicles since actuation is required only in the area of the spot or segment type friction pads and the rotor may be continually cooled during use by ambient air adjacent the wheel. As used herein, "friction pad" and "friction pad means" shall mean a rigid, usually metal, backing plate having friction lining material secured to one or both surfaces thereof with the circumferentially spaced lateral edges of the friction lining material contained within a 90.degree. segment of the rotor to be engaged by the friction pad.
2. Description of the Prior Art
Disc brakes have been known and used with considerable success on automotive vehicles for over the highway use as well as off highway use. Disc brakes utilized in over the highway type vehicles have usually employed a single rotor and a pair of friction pads disposed opposite radially extending surfaces of the rotor and moved into frictional contact with the rotor by fixed or floating actuating means. One such disc brake is disclosed in U.S. Pat. Nos. 4,352,414 and 4,406,352. Off highway vehicles and some aircraft disc brakes have utilzed a plurality of axially movable rotors fixed for rotation with the vehicle wheel and annular type friction rings located between adjacent rotors and secured against rotation to effect a full 360.degree. surface contact between the friction rings and the rotors when the brake is actuated. These vehicles and service requirements are such that the full 360.degree. friction contact between the friction discs and the rotors is generally satisfactory although there have been many efforts to provide means for dissipating thermal energy generated during braking. Some of these have involved the use of cooling fluid where the discs and rotors rotate through a bath of oil. Other systems have utilized pumps for moving liquid coolant into the region of the friction discs and rotors to absorb the thermal energy during actuation of the brake. The space available in the vicinity of an over the road type vehicle wheel and the industry and service requirements for such a vehicle brake are such as to mitigate against the use of a multiple rotor disc brake utilizing a full 360.degree. of surface contact between the rotors and discs.